Installing from RPM is generally better, because:

• you can install and uninstall (properly) python3.
• the installation time is way faster. If you work in a cloud environment with multiple VMs, compiling python3 on each VMs is not acceptable.

Solution 1: Red Hat & EPEL repositories

Red Hat has added through the EPEL repository:

• Python 3.4 for CentOS 6
• Python 3.6 for CentOS 7

[EPEL] How to install Python 3.4 on CentOS 6

sudo yum install -y epel-release
sudo yum install -y python34

# Install pip3
sudo yum install -y python34-setuptools  # install easy_install-3.4
sudo easy_install-3.4 pip

You can create your virtualenv using pyvenv:

pyvenv /tmp/foo

[EPEL] How to install Python 3.6 on CentOS 7

With CentOS7, pip3.6 is provided as a package :)

sudo yum install -y epel-release
sudo yum install -y python36 python36-pip

You can create your virtualenv using pyvenv:

python3.6 -m venv /tmp/foo

If you use the pyvenv script, you'll get a WARNING:

$ pyvenv-3.6 /tmp/foo
WARNING: the pyenv script is deprecated in favour of `python3.6 -m venv`

Solution 2: IUS Community repositories

The IUS Community provides some up-to-date packages for RHEL & CentOS. The guys behind are from Rackspace, so I think that they are quite trustworthy...

https://ius.io/

Check the right repo for you here:

https://ius.io/setup

[IUS] How to install Python 3.6 on CentOS 6

sudo yum install -y https://repo.ius.io/ius-release-el6.rpm
sudo yum install -y python36u python36u-pip

You can create your virtualenv using pyvenv:

python3.6 -m venv /tmp/foo

[IUS] How to install Python 3.6 on CentOS 7

sudo yum install -y https://repo.ius.io/ius-release-el7.rpm
sudo yum install -y python36u python36u-pip

You can create your virtualenv using pyvenv:

python3.6 -m venv /tmp/foo

Python 3.8 Application Stream is currently available with RHEL 8.2 beta. Since we support every new version of Python (3 years) that we release, we need to make sure that it's stable before bringing it to RHEL and the many hardware architectures it runs on. This is also important as customers expect technologies to be production grade. This table shows that over the years, we have officially supported more than one Python version simultaneously. You can download RHEL 8.2 beta from here. RHEL 8 was released with 2 versions of Python (2.7 and 3.6) because it's an important technology for us. We've used it ourselves for many years in building RHEL components and, among others in this industry, we had to rebuild it to 3.x (from 2.7).

FYI - new versions of Python and other components are released as Software Collections on RHEL 7, and as Application Streams on RHEL 8. The benefit of these is that the version of Python that's installed will have exactly the same packages and components for each system it's install it on. This simplifies things a lot (as you point out, it's complicated) and minimizes the "it works on my machine" issue.

Below command worked for me.

sudo dnf install python3.8 -y

I wanted to use python3.8 and removed old python3.6 and installed python3.8 using above command

command to remove python3.6

sudo dnf remove python3.6 -y